Optofluidics is a field that synergizes photonics and micro/nanofluidics to achieve enhanced functionalities in both fluidics and photonic devices. The optofluidic laser is an emerging research area within optofluidics. In general, optofluidic lasers integrate micro/nanofluidics, optical microcavities, and gain material in a liquid environment. Compared to gas- and solid-state lasers, optofluidic lasers are compatible with liquid environments. Accordingly, optofluidic lasers can provide certain advantages for some applications, including some applications that involve aqueous environments, such as some biosensing applications.
In optofluidic laser biosensing, biological processes or events take place inside a laser cavity (rather than a container such as a test tube). Thus, rather than using unamplified fluorescence to detect biological processes or events, optofluidic laser biosensing uses lasing emission. More particularly, a biological process or event causes a change in the gain material associated with the laser cavity, and this change in turn causes a change in the laser output.
Unfortunately, previous optofluidic lasers and methods of optofluidic laser sensing suffer from one or more disadvantages. For example, many previous optofluidic lasers use a bulk solution that contains the gain material, which can be problematic in several regards. First, a large quantity of gain material is generally required to be present in the bulk solution, which lowers the detection sensitivity of the laser and deteriorates the laser performance. Second, in many previous optofluidic lasers, only gain material close to the cavity surface participates in the laser emission. The remaining gain material contributes to undesirable background fluorescence, decreasing the signal to noise ratio (SNR). Other optofluidic lasers are operable only in organic solvents and thus are not biocompatible. Still other previous optofluidic lasers use optical cavities having low Q-factors (e.g., 102-103). Additionally, many previous optofluidic lasers cannot be readily reused or reconfigured, or easily mass-produced to form high-throughput laser arrays including a large number of individual lasing cavities.
Therefore, a need exists for improved optofluidic lasers and methods of making and using optofluidic lasers, including for high-throughput biosensing applications.